This invention pertains to acoustic pulse producing burners adapted for burning gas, liquid or particulate fuels for utility and industrial usage. It particularly pertains to such burners in which acoustic pulsations are self-induced by integral axially moveable Sondhauss thermoacoustic tubular elements to facilitate complete combustion of the fuel.
For reasons of increased combustion efficiency and reduced emissions of combustion products (NO.sub.x, CO, SO.sub.2), pulsed combustion is often utilized in burners for coal, gas or oil fuels. Various designs of such pulsed type burners have been developed and disclosed. For example, U.S. Pat. No. 4,529,377 to Zinn et al discloses a pulse combustor apparatus including a combustor tube having an open end and containing a combustion zone where combusting fuel produces a standing acoustic mode having nodes and anti-nodes in the tube. U.S. Pat. No. 4,699,588 to Zinn et al discloses a pulsating processing system which includes an acoustically resonant processing chamber and a frequency tunable pulse combustor which is positioned to excite natural acoustic modes in the chamber utilizing a swirling motion. U.S. Pat. No. 4,770,626 and U.S. Pat. No. 4,909,731 to Zinn et al disclose a similar tunable pulse combustor useful for chemical, physical and thermal processes, including an acoustically resonant processing chamber and a frequency tunable pulse combustor. Also, U.S. Pat. No. 5,015,171 to Zinn et al discloses a similar improved tunable pulse combustor adapted for moisture removal and particle heating, and including a combustion chamber with an axially translatable acoustic decoupling and flame holder configurations and utilizing axial translation of a flame holder within the combustor.
Although these prior art tunable combustor devices have been found useful, they utilize an acoustic combustion chamber associated with an internal flame-driven pulsating exciter means. However, further burner improvements have been sought and have resulted in the more efficient acoustically pulsating type burner assembly of this invention.